上传文件至 'w11'

w11/ParseStrategies.java

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+import java.time.LocalDate;
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.List;
+import java.util.regex.Pattern;
+
+// ─────────────────────────────────────────────
+// 策略接口
+// ─────────────────────────────────────────────
+interface ParseStrategy {
+    boolean supports(String url);
+    Article parse(String url);
+    String  getName();
+    default int getPriority() { return 100; }
+}
+
+// ─────────────────────────────────────────────
+// 策略实现1：GitHub 专属（priority=10）
+// ─────────────────────────────────────────────
+class GithubParseStrategy implements ParseStrategy {
+    @Override
+    public boolean supports(String url) {
+        return url != null && url.matches("^https?://(www\\.)?github\\.com/.*");
+    }
+
+    @Override
+    public Article parse(String url) {
+        String path  = url.replaceFirst("https?://(www\\.)?github\\.com/", "");
+        String[] parts = path.split("/");
+        String owner = parts.length > 0 ? parts[0] : "unknown";
+        String repo  = parts.length > 1 ? parts[1] : "repo";
+        return new Article("[GitHub] " + owner + "/" + repo, url,
+                           "(GitHub stub)", owner, LocalDate.now());
+    }
+
+    @Override public String getName()    { return "GithubParseStrategy"; }
+    @Override public int    getPriority(){ return 10; }
+}
+
+// ─────────────────────────────────────────────
+// 策略实现2：通用默认兜底（priority=999）
+// ─────────────────────────────────────────────
+class DefaultParseStrategy implements ParseStrategy {
+    private static final Pattern URL_PATTERN =
+        Pattern.compile("^https?://[^\\s/$.?#].[^\\s]*$");
+
+    @Override
+    public boolean supports(String url) {
+        return url != null && URL_PATTERN.matcher(url).matches();
+    }
+
+    @Override
+    public Article parse(String url) {
+        String domain = url.replaceFirst("https?://", "").replaceAll("/.*", "");
+        return new Article("文章来自 " + domain, url,
+                           "(default stub)", "unknown", LocalDate.now());
+    }
+
+    @Override public String getName()    { return "DefaultParseStrategy"; }
+    @Override public int    getPriority(){ return 999; }
+}
+
+// ─────────────────────────────────────────────
+// 策略选择器
+// ─────────────────────────────────────────────
+class StrategySelector {
+    private final List<ParseStrategy> strategies = new ArrayList<>();
+
+    public StrategySelector() {
+        strategies.add(new GithubParseStrategy());
+        strategies.add(new DefaultParseStrategy());
+        strategies.sort(Comparator.comparingInt(ParseStrategy::getPriority));
+    }
+
+    public ParseStrategy select(String url) {
+        return strategies.stream()
+                         .filter(s -> s.supports(url))
+                         .findFirst().orElse(null);
+    }
+
+    public List<ParseStrategy> getAll() { return List.copyOf(strategies); }
+}

w11/Utils.java

@@ -0,0 +1,202 @@
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.function.Supplier;
+import java.util.logging.Logger;
+
+// ─────────────────────────────────────────────
+// 必做1：UrlFormatException（Unchecked / Runtime）
+// 选择 RuntimeException 理由：
+//   URL 格式错误属于调用方编程错误（非法参数），
+//   不应强迫上层 catch，符合 Unchecked 语义。
+// ─────────────────────────────────────────────
+class UrlFormatException extends RuntimeException {
+    private final String invalidUrl;
+
+    public UrlFormatException(String url) {
+        // 保留根因信息，避免"异常包装丢失根因"问题
+        super("URL 格式不合法，必须以 http:// 或 https:// 开头：" + url);
+        this.invalidUrl = url;
+    }
+
+    /** 构造器2：包装底层异常，保留完整调用链 */
+    public UrlFormatException(String url, Throwable cause) {
+        super("URL 格式不合法：" + url, cause);
+        this.invalidUrl = url;
+    }
+
+    public String getInvalidUrl() { return invalidUrl; }
+}
+
+// ─────────────────────────────────────────────
+// 必做2：RetryUtils —— 指数退避重试
+// wait = base * 2^attempt  (base = 500ms)
+// ─────────────────────────────────────────────
+class RetryUtils {
+    private static final Logger log = Logger.getLogger(RetryUtils.class.getName());
+
+    private static final long BASE_MS   = 500;   // 500ms 基准
+    private static final int  MAX_RETRY = 4;     // 最多重试次数
+
+    /**
+     * 执行带指数退避重试的操作
+     * @param task      要执行的任务，返回 true 表示成功
+     * @param maxRetry  最大重试次数
+     * @return true = 最终成功，false = 全部失败
+     */
+    public static boolean retry(Supplier<Boolean> task, int maxRetry) {
+        for (int attempt = 0; attempt <= maxRetry; attempt++) {
+            if (attempt > 0) {
+                long waitMs = BASE_MS * (1L << attempt);   // base * 2^attempt
+                log.info(String.format("第 %d 次重试，等待 %d ms ...", attempt, waitMs));
+                try {
+                    Thread.sleep(waitMs);
+                } catch (InterruptedException e) {
+                    Thread.currentThread().interrupt();
+                    log.warning("重试等待被中断");
+                    return false;
+                }
+            }
+            try {
+                if (task.get()) {
+                    if (attempt > 0) log.info("第 " + attempt + " 次重试成功");
+                    return true;
+                }
+                log.warning("第 " + attempt + " 次尝试失败（任务返回 false）");
+            } catch (Exception e) {
+                log.warning("第 " + attempt + " 次尝试抛出异常：" + e.getMessage());
+            }
+        }
+        log.severe("已达最大重试次数 " + maxRetry + "，放弃。");
+        return false;
+    }
+
+    /** 使用默认最大重试次数 */
+    public static boolean retry(Supplier<Boolean> task) {
+        return retry(task, MAX_RETRY);
+    }
+
+    /**
+     * 选做思考题优化：
+     * 如果某次失败是"永久失败"（如 404），则不应继续重试。
+     * 通过 NonRetryableException 标记不可重试异常，
+     * 捕获到后立即终止重试循环。
+     */
+    public static boolean retryWithFastFail(Supplier<Boolean> task, int maxRetry) {
+        for (int attempt = 0; attempt <= maxRetry; attempt++) {
+            if (attempt > 0) {
+                long waitMs = BASE_MS * (1L << attempt);
+                try { Thread.sleep(waitMs); }
+                catch (InterruptedException e) {
+                    Thread.currentThread().interrupt();
+                    return false;
+                }
+            }
+            try {
+                if (task.get()) return true;
+            } catch (NonRetryableException e) {
+                // 选做思考题：404 / 永久失败 → 立即放弃，不再等待
+                log.severe("不可重试异常，立即终止：" + e.getMessage());
+                return false;
+            } catch (Exception e) {
+                log.warning("attempt " + attempt + " failed: " + e.getMessage());
+            }
+        }
+        return false;
+    }
+}
+
+// ─────────────────────────────────────────────
+// 选做思考题辅助：不可重试异常（如 HTTP 404）
+// ─────────────────────────────────────────────
+class NonRetryableException extends RuntimeException {
+    private final int httpStatus;
+
+    public NonRetryableException(int httpStatus, String url) {
+        super("HTTP " + httpStatus + " 永久失败，不应重试：" + url);
+        this.httpStatus = httpStatus;
+    }
+
+    public int getHttpStatus() { return httpStatus; }
+}
+
+// ─────────────────────────────────────────────
+// 选做：CircuitBreaker（断路器）
+// 状态机：CLOSED → OPEN（连续失败 N 次）→ HALF_OPEN（冷却后）→ CLOSED
+// ─────────────────────────────────────────────
+class CircuitBreaker {
+    private static final Logger log = Logger.getLogger(CircuitBreaker.class.getName());
+
+    public enum State { CLOSED, OPEN, HALF_OPEN }
+
+    private final int  failureThreshold;   // 连续失败多少次触发熔断
+    private final long cooldownMs;         // 熔断后冷却时间
+
+    private volatile State         state          = State.CLOSED;
+    private final    AtomicInteger failureCount   = new AtomicInteger(0);
+    private volatile long          openedAt       = 0;
+
+    public CircuitBreaker(int failureThreshold, long cooldownMs) {
+        this.failureThreshold = failureThreshold;
+        this.cooldownMs       = cooldownMs;
+    }
+
+    /**
+     * 执行一次操作，断路器保护：
+     * - OPEN 状态直接拒绝（不发请求）
+     * - 成功则重置计数器；失败则累加，超阈值触发熔断
+     */
+    public boolean call(Supplier<Boolean> task) {
+        switch (getEffectiveState()) {
+            case OPEN:
+                log.warning("断路器 OPEN，请求被拒绝（冷却剩余 "
+                    + (cooldownMs - (System.currentTimeMillis() - openedAt)) + "ms）");
+                return false;
+
+            case HALF_OPEN:
+                // 半开状态：放一个试探请求
+                log.info("断路器 HALF_OPEN，尝试探测...");
+                if (execute(task)) {
+                    reset();   // 探测成功，恢复 CLOSED
+                    return true;
+                }
+                trip();        // 探测失败，重新熔断
+                return false;
+
+            default: // CLOSED
+                if (execute(task)) {
+                    failureCount.set(0);
+                    return true;
+                }
+                if (failureCount.incrementAndGet() >= failureThreshold) {
+                    trip();
+                }
+                return false;
+        }
+    }
+
+    private boolean execute(Supplier<Boolean> task) {
+        try { return Boolean.TRUE.equals(task.get()); }
+        catch (Exception e) { return false; }
+    }
+
+    private State getEffectiveState() {
+        if (state == State.OPEN
+                && System.currentTimeMillis() - openedAt >= cooldownMs) {
+            state = State.HALF_OPEN;
+        }
+        return state;
+    }
+
+    private void trip() {
+        state    = State.OPEN;
+        openedAt = System.currentTimeMillis();
+        log.severe("断路器已熔断！连续失败 " + failureCount.get() + " 次。");
+    }
+
+    private void reset() {
+        state = State.CLOSED;
+        failureCount.set(0);
+        log.info("断路器已恢复 CLOSED。");
+    }
+
+    public State getState() { return getEffectiveState(); }
+}